An analgesic plays an important role in pain control and especially in cases involving chronic pain. It has heretofore been necessary for a patient to be hospitalized for a long time or to visit a hospital as an out-patient
The need for frequent injection of liquid medicine such as an analgesic or the like is onerous both to a patient and in terms of time and efficiency to a hospital. Consequently, an automatic injection system has been developed which injects liquid medicine to an in-patient periodically and automatically. However, conventional systems are large, expensive, and physically limit a patient.
Therefore, a convenient automatic injection system which is not physically limiting and can be applied to in patients, out-patients, and home-patients has been desired for a long time.
Thus, the applicant has proposed a portable analgesic system (PCT/JP94/00608) which satisfies the above requirements This portable analgesic system comprises a continuous injection for liquid medicine which discharges liquid medicine continuously for a given period of time; a switch valve connected to an outlet of said injector for shutting off discharge of liquid medicine from said injector; a three-way connector to an outlet of said switch valve and having three ways; a flexible reservoir connected to one way of said three-way connector for storing liquid medicine; and a pressure-check valve connected to another way of said three-way connector for opening a flow passage only when a pressure of liquid medicine in said reservoirs rises above a given value.
In the portable analgesic system, a continuous injector for liquid medicine which has a given capacity and a given self-maintaining discharge time is prepared beforehand and a given kind and amount of liquid medicine is injected into the injector in accordance with the condition of a patient. Then, the switch valve is opened to transfer liquid medicine to the reservoir for a given period of time. During such a transference of medicine, a patient can freely move with the system being attached to the body.
A period of time for transferring liquid medicine from the injector to the reservoir coincides with a self-maintaining remedy effect time of liquid medicine. When pain is felt, a patient compresses the reservoir to inject the liquid medicine contained in the reservoir into the body through the pressure-check valve.
In preparation for any subsequent pain, the injector can then be supplied with liquid medicine by a licensee either at the patient's home or at a hospital.
This system has a distinctive effect on the specific condition of patient's disease. However, there are intermittent occasions when the injection of a given amount of liquid medicine into a patient's body is required and therefore administered, e.g., when the patient experiences an irregular or sudden pain. This occurs in parallel with the periodical continuous injection for liquid medicine and in accordance with the ingravescence of the state of the disease, the state of the affected body part and the like.
In this case, a continuous injector for liquid medicine is used in parallel with the portable analgesic system described above. Such a continuous injector for liquid medicine has been developed (Japanese Patent No. 1384289) by the present applicant. This injector includes an inlet portion for liquid medicine, an outlet portion for liquid medicine, and a balloon which connects the inlet portion to the outlet portion. Liquid medicine injected in the balloon flows out through the outlet portion for a long period of time.
However, when using the portable analgesic system in parallel with the continuous injector for liquid medicine, it is necessary to attach to a patient's body two continuous supply units which have substantially the same structures. This is onerous to a doctor or a nurse and is an encumbrance to a patient.